This invention relates to steam decorticators of the type having a pressure vessel for the steam peeling of fruits and vegetables, such as potatoes, and is particularly directed to a venting valve for use on such steam decorticators.
Steam decorticators of the type considered here, are comprised of a steam vessel adapted to receive fruit or vegetables to be peeled. The pressure vessel is rotatably mounted, and is provided with a conduit for introducing steam, a conduit for venting steam, an opening for receiving and discharging the fruits and vegetables, and a closure for closing the opening during the processing of the fruits or vegetables.
A steam decorticator of this type is disclosed, for example, in U.S. Pat. application Ser. No. 469,613 filed May 13, 1974 which discloses a decortication process in which steam is introduced into the pressure vessel following the loading of the vessel with fruits or vegetables and the closure of the closure member. The heated steam increases the pressure and temperature within the vessel, so that the layer of the fruit or vegetable just under the peel comes to a boil when the pressure in the vessel is then rapidly released by way of the venting conduit, to effect the stripping of the peel from the fruits or vegetables. The removal of the peel from the fruits or vegetables is aided by the rubbing of the fruits or vegetables against each other as the pressure vessel is rotated.
In one known construction of such a steam decorticator, as described, for example, in German Pat. No. 1,234,690, the venting valve is a conventional diaphragm type of valve. The valve is connected to the pressure vessel by way of a curved pipe section which extends downwardly from the venting outlet conduit of the pressure vessel, the valve being connected to the lower end of the curved pipe section.
In the decortication of fruit or vegetables in such a system, a considerable quantity of sand and other dirt is entrained in the fluids vented by way of the outlet venting conduit, such sand and dirt having been removed in the pressure vessel from the fruits or vegetables to be peeled. Such sand and other dirt is consequently vented together with the steam, by way of the curved pipe section and the venting valve, for discharge by way of an adjacent stand pipe. In the arrangement of the above German patent, the valve has a small working stroke, and the valve body has a small volume. Consequently, the steam passing through the valve has a high velocity, so that the valve body is subjected to rapid wear by the entrained solids. In addition, the curved pipe section is subject to considerable wear by the solids entrained in the steam, since the sand and other dirt abrade the inner surface thereof, for example, to effect the "sand blasting" of the curved pipe section.
In order to enable a greater appreciation of the above disadvantages of the steam decorticator of the type disclosed in the above German patent, an apparatus of this type will be described in greater detail with reference to FIG. 1 of the drawings.